The invention of this application relates to a pulverizing method and apparatus for effectively pulverizing very difficult to crush scrapped fiber reinforced thermosetting plastic (herein referred to as FRP) generated during production into powder of appropriate size and distribution for the purpose of recycling.
Due to the excellent characteristics of FRP, such as superior hardness, lightness, easy forming of complex configuration parts, FRP is being used actively by various industries and its production volume is increasing yearly throughout the world.
However, in spite of the volume of FRP scraps generated in the production process and FRP products sold in the markets being discarded increasing yearly, nearly most of these are buried in the ground or incinerated but in either case, these disposal methods are unsafe from the point of protection of the environment. Furthermore, no effective recycling is being carried out at all.
By making these scrapped FRP materials into fine powder, it is possible to regenerate FRP into new materials. In other words, not only can the powder be reused by mixing it with virgin resin to form FRP products, it can also be added to other materials such as cement mortar, concrete, paint, and, because of the effects of the above-mentioned special characteristics of FRP has, it is possible to make products having characteristics not found before and consequently, the range of applications is widening in many industries.
The so-called fiber reinforced plastic is resins containing glass fiber as a reinforcing material (GFRP), carbon fiber (CFRP) and organic fiber and as these scrapped materials have excellent durability, high strength, and lightness, they are difficult to crush and it is very difficult to cut the fibers.
The type of thermosetting resin varies depending on the purpose but among these are middle corrosion resist unsaturated polyester resin of the iso group, high corrosion resist unsaturated polyester resin of the bisphenol group, oxidation resist unsaturated polyester resin of the acid group and also, high corrosion resist epoxy resin, etc. For example molded products of GFRP has been widely used as industrial structural materials such as transportation apparatus (automobiles, trains), construction materials (flat/corrugated sheets, sewage tanks, toilet bowls, sundries, helmets, cooling towers, bath units,) etc.
Generally, methods of pulverizing material into powder are roughly classified into (1) crushing by impact stress and (2) breaking up by compression; there are numerous pulverizing apparatus utilizing these processes which have been designed and commercialized. However, there has been no existing pulverizing method or apparatus which satisfied the purpose of effectively pulverizing non-crushable, unbreakable FRP materials to produce an uniform grained powder.
For example, regarding scrapped FRP materials in Japan, the trimming refuse, polymer residues, molding rejects, etc. generated in production are practically all hauled away by outside industrial waste disposal companies for disposal in land fills and these increased cost burdens are oppressing manufacturing business operations. For the users, the volume of scrapped material is positively increasing in housing reforms, etc. In the case of unit bathrooms, 100,000-150,000 yearly and more than 10,000 tons yearly of flat, corrugated are being disposed. Also, there are 220,000 coastal fishing vessels and 100,000 leisure yachts being disposed of and part of these are being abandoned illegally. The large volume of scrapped material is presenting a big problem. From the standpoint of global environmental protection, FRP will not decompose semipermanently when buried in the ground, and when incinerated, the atmosphere is contaminated with waste gas. In addition heavy metals, etc. in concentrated residues can cause secondary pollution problems, etc. In this way, difficult to crush plastics or FRP are widely used in various industries but there are no thorough measures to cope with scrapped materials hereafter and also, no processing technology and method have been established yet.